The steering parts are available through Outdoorking but before you spend money on it there is a bolt that can be loosened off to move the steering shaft to more completely mesh the column teeth into the wedge teeth. It can be knocked out of place by hitting things with the front wheels. I know from experience, I was in the process of buying parts myself when I noticed there was a slightly cleaner patch on the metal where the column had been moved. A few seconds with a spanner and good as gold. Hope it turns out to be that simple for you. If not, the parts are pretty cheap anyway.
